In a semiconductor device manufacturing process, a process of heating a semiconductor wafer (hereinafter referred to as a “wafer”) as a substrate having a chemical solution coated on the surface thereof by a heating device is included. In order to remove a sublimate generated from the chemical solution, the heating process is often performed by mounting the wafer on a heating plate installed within a processing vessel and exhausting the interior of the processing vessel. For example, a semiconductor manufacturing apparatus having a hierarchical structure is sometimes configured such that heating devices are installed at individual levels and heating modules each including the processing vessel are installed in the respective levels. For example, the respective processing vessels installed at the same level are connected to a common exhaust duct through an exhaust pipe provided with a damper. The interior of the exhaust duct is exhausted at a predetermined exhaust flow rate.
In the heating modules, with a view toward the compatibility of increasing film thickness uniformity within a plane of the wafer and reliability of removing a sublimate from the interior of the processing vessel, consideration has been given to changing an exhaust flow rate in the processing vessel while processing one wafer. However, in the aforementioned heating devices, if the exhaust flow rate in one processing vessel is changed, the exhaust flow rate in another processing vessel sharing the exhaust duct with the one processing vessel is also changed. For that reason, it becomes possible that the ability to remove the sublimate from the interior of another processing vessel is reduced and the film thickness uniformity deteriorates.
With regard to the change of the exhaust flow rate in the processing vessel, a description will be made on one example in which three processing vessels are connected to an exhaust duct. It is assumed that the interior of the exhaust duct is exhausted at 30 L/min and further that the respective processing vessels are exhausted at, e.g., 10 L/min, with dampers of exhaust pipes connected to the respective processing vessels kept in an open state. In this state, if the damper of the exhaust pipe connected to one processing vessel is closed and if the exhaust flow rate in one processing vessel becomes equal to 0 L/min, the exhaust flow rate in the remaining two processing vessels is increased to 30/2=15 L/min. This is because the interior of the exhaust duct is exhausted at 30 L/min.
For example, a heating device which, while processing a wafer, changes a supply amount of a purge gas supplied into a processing vessel is known. There is also known a liquid processing device in which a plurality of cups is connected to a common exhaust duct through exhaust pipes having dampers and in which the exhaust flow rates in the respective cups are controlled independently of one another. However, these devices are not capable of solving the aforementioned problem.